Please Help !!! fixing a Tone Bone Plexitube Distortion Pedal

Hi,
I've connected my ToneBone plexitube Hot British Distortion Pedal to a MOOER PowerBank.
first to the 15V and the power bank shut off.
then i've tried connecting it to the 12V and after a few seconds smoke came out.
Upon inspection it seems that only the capacitor got burnt -
I'm hoping that it is only a matter of replacing this capacitor.
However because it is burnt i can't know what capacitor to buy.
the capacitor definitely looks burnt but it tweets on continuity check in the multimeter.
I don't know much about electronics and can't figure out what to do. the schematics for other products don't realy help me -
The capacitor is C21 in the Plexitube Hot British Rev 0A 29-8.
I'm hoping someone here can help me figure out this otherwise I'd have to go to a propper lab to get it fixed.
I've sent a help request to Radial Engineering Hoping they'd help me.
Thank you.

Hi,
I've connected my ToneBone plexitube Hot British Distortion Pedal to a MOOER PowerBank.
first to the 15V and the power bank shut off.
then i've tried connecting it to the 12V and after a few seconds smoke came out.
Upon inspection it seems that only the capacitor got burnt -
I'm hoping that it is only a matter of replacing this capacitor.
However because it is burnt i can't know what capacitor to buy.
the capacitor definitely looks burnt but it tweets on continuity check in the multimeter.
I don't know much about electronics and can't figure out what to do. the schematics for other products don't realy help me -
The capacitor is C21 in the Plexitube Hot British Rev 0A 29-8.
I'm hoping someone here can help me figure out this otherwise I'd have to go to a propper lab to get it fixed.
I've sent a help request to Radial Engineering Hoping they'd help me.
Thank you.

Near as I can tell, the tonebone wants 15V, tip positive. The MOOER supply is tip negative, so it is the wrong polarity for this pedal.
Most likely components that got fried are shown as D1 and C27A on the schematic posted by nosaj.

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Just because they don't have tubes doesn't mean they don't have feelings! - glebert

Near as I can tell, the tonebone wants 15V, tip positive. The MOOER supply is tip negative, so it is the wrong polarity for this pedal.
Most likely components that got fried are shown as D1 and C27A on the schematic posted by nosaj.

I was kinda thinking that might've been a possibility but didn't get to researching the mooer.

nosaj

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Binkie McFartnuggets‏:If we really wanted to know the meaning of life we would have fed Stephen Hawking shrooms a long time ago.

PICS

thanks for the quick reply.
here are the picshttps://ibb.co/QQc6ytq
to the left between the DC in Jack and the potentiometer is the burnt capacitor
also below the 4th potentiometer from the right there is something that might be burnt plastic which i haven't noticed at the begining.
a pic of the small plastic blob https://ibb.co/x1rZ9Q8
to the left of the dc jack the burnt capacitor https://ibb.co/b6kPBnG
does anyone know if i'm elligible for warranty after making such a stupid mistake ? it's brand new and i barely used it.

i also ask if i can use continuity check on a powered on board like this or is it too risky ?
do capacitors and resistors respond to a continuity check ?

yes your'e right. the funny thing is that when connecting to 12v the mooer didn't shut down while in 15v it did. the polarity is the opposite to boss effects which work fine. such a stupid mistake. lesson learned the hard way.
Thank you for the reply - much appreciated.

the c27a says 47/16 - what does that mean ? what should i ask for in the store ?
also the diode D1 - should i just ask for a 1N4001 diode ?
how do i know which way to connect the capacitor - the black and white on the schematic what is the positive and what is the negative ?
also how do i tell the positive and negative on the newly purchased capacitor ?
i apologize for asking such novice questions but all i know about electronics is from a fourth grade hobby course. :-)
thanks.

thanks for the quick reply.
here are the picshttps://ibb.co/QQc6ytq
to the left between the DC in Jack and the potentiometer is the burnt capacitor
also below the 4th potentiometer from the right there is something that might be burnt plastic which i haven't noticed at the begining.
a pic of the small plastic blob https://ibb.co/x1rZ9Q8
to the left of the dc jack the burnt capacitor https://ibb.co/b6kPBnG
does anyone know if i'm elligible for warranty after making such a stupid mistake ? it's brand new and i barely used it.

i also ask if i can use continuity check on a powered on board like this or is it too risky ?
do capacitors and resistors respond to a continuity check ?

Thanks for the support very much appreciated.

The piece of black plastic your reference is most likely the outer sheath of the capcaitor.
Warranty, not likely.
Continuity check on a powered board? Don't even think about it, Now with no power connected then yes it's ok, just don't plug it in. When it's powered you will use the voltage portion of the meter.

nosaj
Depending on the DVM resistors will up to a point choose Ohms and verify by the stripe code.

0

Binkie McFartnuggets‏:If we really wanted to know the meaning of life we would have fed Stephen Hawking shrooms a long time ago.

the c27a says 47/16 - what does that mean ? what should i ask for in the store ?
also the diode D1 - should i just ask for a 1N4001 diode ?
how do i know which way to connect the capacitor - the black and white on the schematic what is the positive and what is the negative ?
also how do i tell the positive and negative on the newly purchased capacitor ?
i apologize for asking such novice questions but all i know about electronics is from a fourth grade hobby course. :-)
thanks.

47uf 16v Which means the caps are riding on the edge, I'd at least put in a 25v. Probably easier to get a 1n4007 which will work the same.

How else you gonna learn if you don't ask?

The only stupid question is the one you don't ask.
nosaj

4

Binkie McFartnuggets‏:If we really wanted to know the meaning of life we would have fed Stephen Hawking shrooms a long time ago.

Thanks nosaj i really appreciate the help. i am afraid of touching the board but it seems that i have no choice. i have a 65W soldering iron and i ordered one with thermal control. what temperature should i use so i don't do more damage ?
I'll wait a couple of days and see if i get an answer from Radial.

Thanks nosaj i really appreciate the help. i am afraid of touching the board but it seems that i have no choice. i have a 65W soldering iron and i ordered one with thermal control. what temperature should i use so i don't do more damage ?
I'll wait a couple of days and see if i get an answer from Radial.

Since this will be your first foray.. please go find a broken electronic device somewhere, open it up and start removing things. My iron uses Celcius I usually have mine set around 390-400C , I will also use some new solder to wet what I want to remove it seems to make it easier to remove when using a solder sucker. Solder wick I've never successfully used so I can't comment on that.
Always practice something new first on a donor.

nosaj

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Binkie McFartnuggets‏:If we really wanted to know the meaning of life we would have fed Stephen Hawking shrooms a long time ago.

yes i've started practicing.
radial just answered me - "
I am sorry to hear about your Plexitube. All Radial and Tonebone devices that require our 15V power supply are all fed with a center-pin positive polarity.
The Mooer power supply supplies center-pin negative polarity only—it sounds as if you fed your Plexitube with the incorrect polarity.
The capacitor at C21 is a 10µF 35V tantalum capacitor.
Further, I spoke with my service technician about your Plexitube. He recommended changing the diode at D1 as well since this occurred. The diode is a 1N4001 diode."
so g1 got it right with the diode.
i'm not sure how to deal with the black blob thing - either try to remove the blob without damagin the board from above or desoldering from below and then taking out the blob mass - lol
Thanks again

yes i've started practicing.
radial just answered me - "
I am sorry to hear about your Plexitube. All Radial and Tonebone devices that require our 15V power supply are all fed with a center-pin positive polarity.
The Mooer power supply supplies center-pin negative polarity only—it sounds as if you fed your Plexitube with the incorrect polarity.
The capacitor at C21 is a 10µF 35V tantalum capacitor.
Further, I spoke with my service technician about your Plexitube. He recommended changing the diode at D1 as well since this occurred. The diode is a 1N4001 diode."
so g1 got it right with the diode.
i'm not sure how to deal with the black blob thing - either try to remove the blob without damagin the board from above or desoldering from below and then taking out the blob mass - lol
Thanks again

Based on that it probably stands to reason the schematic I posted is not the same as your board.
nosaj

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Binkie McFartnuggets‏:If we really wanted to know the meaning of life we would have fed Stephen Hawking shrooms a long time ago.

The burnt yellow cap next to the power jack is definitely a tantalum cap, so get one like they told you, to replace it. The board will probably be marked with a polarity marking to show you how to install the new one. The new cap will have a polarity marking on it or at least the two leads will be of different lengths to show the polarity.

The black blob is epoxy or encapsulation medium put on the board to cover up part of the circuit that the manufacturer does not want people to see. You probably will not need to do anything with it, in order to fix the pedal.

i'm so relieved to hear that. so i hope this should be quite an easy repair. that was my initial thought but then my mind started going for worst case scenarios. :-)
Thanks Bill

My worst-case scenarios always involve me being impatient. So my advice is take it slow. And practice on some broken thing before you approach the pedal - as advised before.

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If it still won't get loud enough, it's probably broken. - Steve Conner
If the thing works, stop fixing it. - Enzo
We need more chaos in music, in art... I'm here to make it. - Justin Thomas
MANY things in human experience can be easily differentiated, yet *impossible* to express as a measurement. - Juan Fahey

hi,
some progress made - i've replaced the capactior and the diode. the shop gave me a 1N4007 instedat of a 1n4001 and just like nosaj said it should work.
i was so thriled that it did turn on but it sounds like this - (the changes in volume is because i'm turning the pedal's level knob while recording)https://we.tl/t-gUqUmUh9rS
then i took out the 4007 and replaced it with the original 4001 and it turned on but still sounds like some power tool :-)
where should i go from here ?

hi,
some progress made - i've replaced the capactior and the diode. the shop gave me a 1N4007 instedat of a 1n4001 and just like nosaj said it should work.
i was so thriled that it did turn on but it sounds like this - (the changes in volume is because i'm turning the pedal's level knob while recording)https://we.tl/t-gUqUmUh9rS
then i took out the 4007 and replaced it with the original 4001 and it turned on but still sounds like some power tool :-)
where should i go from here ?

To say this could be a very involved repair is an understatement. We do not have a schematic that correlates to your board, so there will be guesses here.
Based on your info provided and the schematic I found I am thinking you replaced C6 on the schematic I have. If that has any similarity to your board then it's very possible U4 is out (I'm not real sure if Voltage regulators handle reverse polarity or not).

The only things I can think of to see if anything can be narrowed down is to pull the tube and see if it's still making noise, see if the switches changed removed the noise(with and with out the tube). Check the voltage at pins 1 and 6 on the tube socket.

Just understand we're working on for example here's an anology. Say we have a map of Florida from the 1950's and we're now in 2019. A lot of things can be very similar but also different.

nosaj

1

Binkie McFartnuggets‏:If we really wanted to know the meaning of life we would have fed Stephen Hawking shrooms a long time ago.

hi,
some progress made - i've replaced the capactior and the diode. the shop gave me a 1N4007 instedat of a 1n4001 and just like nosaj said it should work.
i was so thriled that it did turn on but it sounds like this - (the changes in volume is because i'm turning the pedal's level knob while recording)https://we.tl/t-gUqUmUh9rS
then i took out the 4007 and replaced it with the original 4001 and it turned on but still sounds like some power tool :-)
where should i go from here ?

Did you verify (by measuring inside the pedal) that the pedal actually gets full 15V from the powerbank? This is also to make sure that the powerbank still works properly and wasn't damaged by the wrong polarity connection.

If so the next step would be to verify the 12V after 7812 regulator which feeds the tube heater and then the +/- 6V opamp supply voltages.

ok first thanks a lot about the help everybody !!!
Helmholtz - I am using a 15v stabilized transformer. the Mooer powerbank is fine.
1. now some question for nosaj you said to check the pins - and Helmholtz you said to check the voltage - but how can i check if the power is down - nosaj you said not to check when the circuit is on ?
2. are these voltage regulators - https://upload.wikimedia.org/wikiped..._regulator.jpg
and if so do you mean the one just to the right of the capacitor i replaced (labeled Q1 in my pedal) or the two below the fifth potentiometer from the right (labeled Q7 and Q8) ? or all of them.
3. what is U4 I can't find any U on the circuit ?

i also thought maybe I should reverse the capacitor maybe i put it wrong ?
Thanks.

What do you mean with stabilized transformer? A regulated DC power supply?

1. now some question for nosaj you said to check the pins - and Helmholtz you said to check the voltage - but how can i check if the power is down - nosaj you said not to check when the circuit is on ?

To check operating voltages, the circuit has to be powered.

The Uxs in the schematic of post #2 are designators of integrated circuits. The Qs mean transistors.

I suggest to start with measuring the heater voltage of the tube between pin #4 and #5. Should be 12VDC. Pin #4 and PIN #5 should each measure +/- 6VDC to circuit ground.

As already noticed, the reference numbers/labelling of components may differ from schematic to actual circuit board. And we are not sure if the schematic is valid.

Hi Helmholtz - yes it's a regulated DC power supply.
regarding the IC's - as far as i can tell there are only two visible - maybe there's also one in the epoxy covered as well - anyway, one says -
O72D
JRC
H023B

and the other reads:
OP725
G #1711
3776788

i am getting approx 14.6V on the 7821 voltage regulator.

now the tube is a crecent so looking from the outside where the joints are made i am going clockwise counting from the hollow of the crecent - so between 4 and 5 there is 14.5V.

nosaj sorry for the question - only continuity is forbidden - now i get it.

offtopic question

where the lines cross but there's no dot that marks a connection neither a loop above that marks they are not crossed - like the line going from C1 down - is it connected with the line going down from leg 1 of the 555 ?

and also do you have a recommendation for some basic beginner's guide - book, videos whatever works ?

Helmholtz so, do you recommend trying to change the voltage regulator and see where to continue from there ?

It is probable that there is more damage than just the regulator IC. If you don't understand what you are doing, you might easily cause more damage.This might be a job for a professional technician with signal generator and scope.